exam 4- brain + cranial nerves

dura mater

the outer layer

strong + fibrous

bi layer:

• periostea

• meningeal

dural septa

inward extensions

fall cerebri + tentorium cerebelli

dural venus sinuses

venous blood

return CSF to blood stream

arachnoid mater

middle layer

spiderweb- like

pia mater

innermost layer

lines brain + spinal cords surface

contains blood vessels

filum terminale

subdural spaces

film of fluid

subdural hematoma

subarachnoid space

cerebrospinal fluid

arachnoid villi/ granulations

CSF function

protection

circulating fluid reservoir

• brain monitors CO2

lateral ventricles (2)

in cerebral hemispheres

3rd ventricle

thin vertical pocket

4th ventricle

tiny & diamond shaped

continues as central canal of cord

chorioid plexuses

Cerebrospinal formation

capillary networks

projection from Pia mater into ventricles

covered by ependymal cells

plasma separated from blood

CSF- midsagittal view

brain capillaries

blood brain barriers

endothelial cells

• TIGHT JUNCTIONS

basement membrane

astrocyte feet

stops most substances & all cells

allows diffusion- lipids & gases, ETOH, nicotine, caffeine

allows facilitated diffusion &

medulla oblongata

pyramids

• pyramidal (corticospinal) tracts - DECUSSATE

olives

• nuclei for muscle & joint stretch reflexes ( relays to cerebellum)

inferior cerebellar peduncles ( tracts to cerebellum_

nuclei

• cardiac, respiratory, vasomotor control centers

• vomit, sneeze, hiccup, cough, swallow

• CNS VIII, IX, X, XI, & XII

pons

“bridge”

conduction tracts connect cerebrum → cerebellum

• middle cerebella peduncles

nuclei

• CNs V, VI, VII & VIII

pneumotaxic centers- respiration

midbrain- mesencephalon

cerebral peduncles

• impulses btw midbrain & cerebrum

CN III-IV

midbrain: superior cerebellar peduncles

impulses from cerebellum

midbrain: corpora quadrigemina

superior colliculi- visual reflex

inferior colliculi- auditory reflex

red nucleus- muscle control

midbrain: substantia nigra (nucleus)

muscle control

dopamine

• Parkinson’s disease

brainstorm functions

passageways for spinal tracts

reflex centers

cerebellum

hemispheres

lobes

geri

sulci

Folia

outer gray matter= Cortex

arbor vitae

inner white matter

long tracts

inferior cerebellar peduncles ← medulla o. & spinal cord

long tracts 2

middle cerebellar peduncles ← pons

long tracts 3

superior cerebellar peduncles → midbrain

cerebellum functions

movement planning & coordination

posture

balance

sensory data coordination for cerebrum

Thalamus

diencephalon

dumbbell shaped

relay station

lateral masses

• superolateral walls of 3rd ventricle

interthalamic adhesion - “dumbbell handle”

gray matter- complex arrangement of nuclei

• geniculate bodies (nuclei)

  • auditory relay

  • visual relay

thalamus functions

prioritizes & relays impulse to & from cerebrum

sensation of thalamus

conscious recognition of pain, temperature & touch

relaus extensive sensory impulses to cerebrum

emotional responses

arousal- conscious v. unconscious

complex reflex movements

hypothalamus

diencephalon

inferolateral walls of 3rd ventricle

mamillary bodies

• olfactory relays

• involved in memories

infundibulum

• pituitary gland

hypothalamus- functions

nervous & endocrine

• pleasure centers

• ANS regulation

• relay station btw cerebrum & ANS effectors

  • mind-body connection

• hormone production

  • water balance & labor (childbirth)

• hormone control over anterior pituitary secretion

  • growth, metabolism, reproduction, water balance, lactation

• temperature regulation

• appetite regulation

epithalamus

roof of 3rd ventricle

pineal gland

• biologic clock regulation

• melatonin

cerebral tracts : connective

tracts- white matter

association

protection

commissural: corpus collosum

basal ( cerebral) nuclei

gray matter islands

• caudate nucleus

• putamen

• globus pallidus

• amygdaloid body

“filter” or fine-tune

• movement

• cognition

• emotion

cerebral localization

primary cortical areas of specific function

postcentral gyrus

primary somatic sensory area

• stimuli ascend for conscious feeling of heat, cold & touch

pre central gyrus

primary somatic motor area

• stimuli descend to skeletal muscles

transverse gyrus

primary auditory area

occipital lobe

primary visual area

somatic senses: cerebrum function

primary somatic sensory area

• post central gyrus

• touch, pressure, temperature & body position

• register sensations

• relay information

motor control: cerebrum functions

primary somatic motor area

• pre central gyrus

  • control individual muscles

• anterior to pre central gyrus

  • activate muscle groups

integrative functions

sensory reception → integration→ motor output

aspects of integration

• consciousness

• language

• emotions

• memories

CONSCIOUSNESS = AWARENESS= ALERTNESS

reticular activating system ( RAS)

spinal cord → reticular formation → thalamus → cortex

reticular formation= loose chain of nuclei along brain stem & midbrain

• relieves sensory impulses

• continuously sends impulses to thalamus

arousal or alert system

filters data

maintains consciousness ( wakefulness)

limbic system emotions

experience & expression

“emotional visceral brain”

around corpus callous & fornix

multiple brain connections

• connects higher level cortex & more primitive brainstem

• emotion-body connections

• regulation of emotions

limbic system 2

amygdaloid body

cingulate gyrus

hippocampus

projections to prefrontal cortex

influences hypothalamus activity

linked with smell & memory

language

acts & interpretation of speaking writing

left hemisphere (90%)

• lateralization

broca’s area ( frontal lobe)

• expressive aphasia

  • unable to articulate words

wernicke’s area ( temporal & parietal lobes)

• receptive aphasia

  • unable to understand words

memory

short term (working): secs or minutes

long term- days or years

involves multiple lobes

synaptic structural changes

increase # presynaptic axon terminals '

increase # postsynaptic receptor proteins

increase synaptic neurotransmitter concentration

astrocyte activity

linked to limbic system

“ NEURONS FIRE TOGETHER WIRE TOGETHER!”

primary sensory neuron: SSP

cell body in DRG

receptor spinal nerve → spinal cord

secondary sensory neuron: SSP

cell body in posterior horn

spinal cord ascending spinal tract → thalamus

• fibers decussate in spinal cord

tertiary sensory neuron

cell body in thalamus

thalamocorticar tracts → thalamus postcentral gyrus

pre central gyrus: SMP

cells in somatic brain

motor upper motor neuron → steam & spinal cord

descending spinal cord tracts

spinal cord

cell bodies in anterior horn

spinal cord → lower motor neuron

muscle fibers (spinal nerve)

• usually involve interneurons

functional classification: excitatory v. inhibitory

upper motor neuron lesions

CNS damage: control from motor cortex lost

spinal reflexes haphazardly stimulate muscles

“spastic”

Lower motor neuron lesion

spinal nerve damage

no stimulation to muscle

atrophy

weakness

“flaccid paralysis”

oh no I step on a nail

pain ( SSP) → cry (limbic system) → scream (Broca speech) → pick up foot (SMP) → look at nail in foot (visual cortex) → alarmed (reticular activating system)